The rare beaked whale discovered Tuesday night on Venice Beach likely had been dead and decomposing for some time before drifting ashore, a marine mammal specialist said Friday.

The mammal, tentatively identified as a Stejneger's beaked whale, had no signs of trauma inside or outside its body, nor any obvious sign of disease, said Jim Dines, Mammalogy Collections Manger at the Los Angeles County Natural History Museum, where a necropsy was performed Wednesday.

The whale's head was sent out for a CT scan, along with organ tissue samples that will be examined for parasites or disease, Dines said. The scan could examine whether the whale, a female, might have suffered damage from the U.S. Navy's use of under-surface sonar, to which beaked whales are sensitive, he added.

The animal's DNA also will be analyzed to resolve its species, Dines said.

Some witnesses had reported that the mammal was alive when it washed ashore, but that was not consistent with the state of decomposition evident in the body, Dines said.

"The only thing significant is the stomach was empty," said Dines. "It did have some nylon braiding but nothing that would cause a significant blockage."

Some of the animal's ribs were broken, but those injuries likely occurred after death, he added.

The museum will add the animal's skeleton to its collection of more than 4,000 marine mammal skeletons, the second largest repository in North America.

Stejneger's beaked whales normally roam deep, cold waters of the northern Pacific Ocean, and are rarely seen close to California's shores. The last time one washed up here was about 15 years ago, according to Dines.